In college, when our money got thin, my roommate instituted what he called "freezing in the dark." The thermostat was dialed down, the lights went out, and the utility bill plunged. I can't say I always enjoyed it. At times I imagined we could store frozen hamburger on our bookshelves,...

On Star Trek: The Next Generation, crew members get their food from microwave-like dispensers in their bedrooms called "Replicators." They walk up and mumble something and a lovely beef Wellington sparkles into existence. It's the ultimate vending machine, and nothing ever costs a dime.